Hand-held pipettor

ABSTRACT

A hand-held pipettor comprising a piston received in one end of a cylinder, a pipettor tip removably secured to an opposite end of said cylinder, means for reciprocating said piston through a selected stroke to aspirate fluid into and to expel the thus aspirated fluid from said pipettor tip, mutually spaced stop members operatively associated with said manually driven means for defining the range of said stroke and motor driven means for varying the spacing between said stop members to thereby vary the volume of fluid being aspirated into and expelled from said pipettor tip.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority of provisional patent application Ser.Nos. 60/329,704 and 60/329,706, each filed on Oct. 16, 2001.

FIELD OF THE INVENTION

The present invention relates generally to transfer and dispensingdevices for liquid reagents and samples, and more particularly tohand-held pipettors.

BACKGROUND OF THE INVENTION

Pipetting systems are widely utilized in laboratories and hospitals forwithdrawing and dispensing relatively small, predetermined quantities ofliquids from one location to another, such as between test tubes,microplates and other liquid receptacles. Portable, or hand-held,pipettors are one type of pipetting system. Hand-held pipettorsgenerally include a housing, a cylinder including two cylinder ends,with one end positioned within the housing and the other end extendingfrom the housing to form a pipettor tip holder, a piston that moveswithin the cylinder to withdraw liquid from a supply receptacle anddispense the liquid to a receiving receptacle, and a plunger that drivesthe piston. While not a permanent part of the pipettor, a disposablepipettor tip is commonly attached to the end of the tip holder to retainthe liquid to be transferred. This tip can be removed from the tipholder, disposed of, and replaced with a new tip. These hand-heldpipettors may be configured to transfer liquids by automated or manualactuation of the pipettor. Automatically operated hand-held pipettorsgenerally include a motor for actuating the plunger to move the pistonwithin the pipettor cylinder for liquid transfer. Manually operatedhand-held pipettors require the pipettor user to apply force to theplunger head, usually with a thumb or a finger, to actuate the piston.

Hand-held pipettors may be designed as fixed volume pipettors, whereonly one predetermined liquid volume is withdrawn and dispensed, or asadjustable pipettors, where the user may set a desired volume to bedispensed within a given volume range. Stop features located within apipettor determine the distance that a piston will travel, also known asthe stroke. The stroke corresponds to the volume of liquid to bewithdrawn and dispensed. Hand-held pipettors commonly include two stopsto establish the limits of the stroke. For purposes of the foregoingdescription, these two stops will be referred to as a front stop and arear stop. In this description, the front stop is the stop closest tothe tip holder and the rear stop is the stop closest to the plungerhead, or in a manual pipettor, the end of the plunger that is manuallyactuated by a pipettor user. The stops in a fixed volume pipettor arefixed, and the piston travels the same stroke during each completeactuation of the plunger. In an adjustable volume pipettor, at least oneof the stops is movable to adjust the stroke length of the piston, andthus the volume to be withdrawn and dispensed.

In manual pipettor applications where the volume of liquid to betransferred may vary frequently within a single application, thepipettor user must frequently change the volume settings on thepipettor, which can cause fatigue and potentially inaccurate volumesettings on the pipettor.

SUMMARY OF THE INVENTION

In one embodiment of the invention, a hand-held pipettor comprises ahousing including a front stop and a rear stop, a cylinder, a pistonthat moves within the cylinder to draw and expel liquid, and a plungerthat moves the piston, the rear stop being movable by a motor to adjustthe volume of liquid to be aspirated and dispensed by the pipettor.

In another embodiment of the invention, the pipettor includes a voicerecognition system that coacts with a central processing unit totranslate verbal commands for volume settings into electronic signalsthat control the motor moving the rear stop.

In another embodiment, a hand-held pipettor for dispensing specificliquid volumes comprises a cylinder having one end defining a tip holderthat accepts a disposable pipettor tip, a piston that moves within thecylinder to withdraw and dispense liquid, and a manually actuatedplunger that moves the piston to at least one point of resistance, thehousing containing a tactile blow-out mechanism that facilitates manualexpelling of a remnant liquid in the pipettor tip following thedispensing of specified liquid volumes. The blow-out mechanism requiresthe pipettor user to apply a force to the plunger through a first pointof resistance to a second point of resistance to expel remnant liquidfrom the pipettor tip.

In a further embodiment, a hand-held pipettor for pipetting applicationscomprises a cylinder having and end configured and arranged to accept adisposable pipettor tip, a piston that moves within the cylinder towithdraw and dispense liquid, a plunger that moves the piston, and amanually actuatable tip ejector assembly configured and arranged todislodge the pipettor tip for disposal following a pipettingapplication.

These and other features and advantages of the present invention willnow be described in greater detail with reference to the accompanyingdrawings, wherein:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a vertical sectional view taken through a manual hand-heldpipettor in accordance with the present invention;

FIG. 2 is a horizontal sectional view on an enlarged scale taken alongline 2—2 of FIG. 1;

FIG. 3 is an enlarged view of a portion of FIG. 1; and

FIG. 4 is a schematic diagram of the voice recognition system.

DETAILED DESCRIPTION

A pipettor in accordance with the present invention is generallyindicated at 10 in FIG. 1. The pipettor includes a housing 12 with anaxially projecting cylinder 14. Cylinder 14 has a tapered distal enddefining a pipettor tip holder 16. A pipettor tip 18 is removablysecured by friction to the tip holder 16. The opposite end of thecylinder has an enlarged head 20 with an internal ledge 22 on which isseated an O-ring 24 supporting an apertured seal 26. A sleeve 28 has anapertured lower end 30 received in the cylinder head 20. The sleeve 28has an intermediate interior shoulder 32 and an internally threaded openupper end 34. A front stop collar 36 is biased upwardly against theinternal shoulder 32 by a spring 38.

A piston 40 in the cylinder head 20 projects downwardly through the seal26. The piston is biased upwardly against the lower end of a plunger 42by a main spring 44. Plunger 42 extends upwardly through the aperturedlower end 30 of sleeve 28, and through the front stop collar 36 and atubular externally threaded screw 46, with its upper end projecting fromthe top of the housing 12 and into an axially depressable cap 48.

An enlarged intermediate section 58 of the plunger 42 defines upper andlower shoulders 52 and 54. Shoulder 52 is biased against the lower endof the screw 46 by the force of the main spring 44 acting on the piston40. The lower screw end thus serves as a rear stop.

As can best be seen by additional reference to FIG. 2, the upper end ofthe screw 46 is provided with external ribs 56 slidably received ininternal grooves 57 in a rotatable drive collar 60. An external gear 62on the drive collar 60 meshes with a drive pinion 64 on the output shaftof a motor 66.

Actuation of motor 66 will cause the drive collar 60 to rotate, and themechanical interengagement of the ribs 56 and grooves 57 will result ina corresponding rotation being imparted to the screw 46. The threadedengagement of the screw 46 with the upper end 34 of the fixed sleeve 28will result in the screw being shifted axially to a desired setting ofits lower end, which provides a rear stop for the plunger 42 and thepiston 40 biased agains its lower end by the main spring 44.

The setting of the rear stop will limit the extent to which the piston40 can be retracted from the tubular portion of the cylinder 14, whichin turn will control the volume of liquid that can be drawn into thepipettor tip 18 during aspiration.

Aspirated liquid is dispensed from the pipettor tip by manuallydepressing the cap 48 to advance the plunger 42 and the piston 40against the biasing force of the main spring 44. The plunger willcontinue to advance until the lower shoulder 54 of its enlargedintermediate section 58 engages the front stop 36, creating a firstpoint of resistance which indicates that most of the aspirated liquidhas been dispensed. By manually applying additional force to the plunger42 in order to overcome the resistance of spring 38, the piston will beadvance further to insure that any residual liquid will be “blown out”of the pipettor tip 18.

In another aspect of the invention, the pipettor includes a tip ejectorassembly generally indicated at 68 for removing a pipettor tip 18 fromthe pipettor tip holder 16. As can best be seen by a combined referenceto FIGS. 1 and 3, the tip ejector assembly 68 includes a tip ejectoractuator 70, a tip ejector shaft 72, a tip ejector sleeve 73 movablewith the tip ejector shaft, and a lock collar 74. The lock collar allowsone way movement of the tip ejector shaft 72 and sleeve 73 in thedirection of arrow A in FIG. 3, but does not allow movement of thesecomponents in the opposite direction, the direction of arrow B, when thelock collar is oriented in its locking position, as illustrated.Therefore, when a disposable tip 18 is wedged upwardly onto the tipholder 16, the tip ejector sleeve 73 is pushed upwardly in the directionof arrow A. At the same time, the tip ejector shaft 72 will also move upa distance equal to the distance traveled by the tip ejector sleeve dueto the fixed connection therebetween. The lock collar 74 will allowmovement of the tip ejector shaft 72 in the direction of arrow A withoutresisting movement. However, the tip ejector shaft 72 will be preventedfrom moving in direction B toward the disposable tip 18 by the lockingaction of the lock collar 74.

A spring 76 is positioned to bias the lock collar into an angled, orlocking position. The spring 76 keeps the tip ejector shaft 72 locked bythe lock collar 74, and thus prevents the tip ejector shaft and theejector sleeve 73 from moving in the direction of arrow B to dislodgeand eject the pipettor tip 18.

Depressing the tip ejector actuator 70 in the direction of arrow C willcause its tapered lower end 78 to coact with a mating inclined surfaceof a ramp wedge 80, causing the ramp wedge to shift in the direction ofthe lock collar, and creating a force lifting the lock collar from itsangled locked position to a raised unlocked position. Once the lockcollar is unlocked, the tip ejector shaft is released to move throughthe lock collar in the direction of arrow B under the force of spring82. The tip ejector sleeve 73 will be correspondingly moved, causing thepipettor tip 18 to be dislodged and ejected from the end of the pipettortip holder 16.

In another embodiment of the invention, a damper mechanism includes apiston 84 formed at the upper end of the tip ejector shaft 72. Thepiston is encircled by an O-ring seal and enclosed in a chamber 86vented to atmosphere by a one way check valve 88. Movement of the tipejector shaft in direction A causes air to be expelled from the chamber86 via the check valve, whereas movement in direction B is retarded bythe rate at which air can be readmitted to the chamber via a smallerbleed hole 90. The retarded rate of travel in direction B beneficiallyretards the velocity at which the pipettor tip is ejected.

In another embodiment of the invention, as can be seen by reference toFIGS. 2 and 4, the adjustment drive collar 60 is surrounded by anencoder wheel 92 that rotates with the adjustment drive collar and thatcomprises part of an encoder assembly 94. The pipettor includes a voicerecognition system VRS that translates verbal commands 96 for volumesettings and outputs the result 98 to a central processing unit CPU. TheCPU generates an electronic signal 99 that controls the motor 66, andmay optionally receive input 100 from the encoder assembly 94 indicativeof the position of the adjustable stop. The pipettor's adjustmentmechanism is thus moved automatically to the position corresponding tothe voice input setting.

In light of the foregoing, it will be understood by those skilled in theart that although the present invention has been described withreference to a pipettor having a manually actuated piston, certainaspects of the invention including the motor driven stop adjustmentmechanism, the voice recognition system, and the tip ejection mechanism,are also applicable to pipettors having motor driven pistons.

Modifications and improvements within the scope of the present inventionwill become apparent to those skilled in the art. The above descriptionis intended to be purely illustrative, and does not define the limits ofthe present invention.

1. A hand-held pipettor comprising: a piston received in one end of acylinder; a pipettor tip removably secured to an opposite end of saidcylinder; manually driven means for reciprocating said piston through aselected stroke to aspirate fluid into and to expel the thus aspiratedfluid from said pipettor tip; mutually spaced stop members operativelyassociated with said manually driven means for defining the range ofsaid stroke; a voice recognition system that decodes verbal commands andoutputs the result to a central processing unit, which in turn generatescontrol signals; and motor driven means for varying the spacing betweensaid stop members to thereby vary the volume of fluid being aspiratedinto and expelled from said pipettor tip, said motor driven meansincluding a drive motor mechanically coupled to one of said stopmembers, said drive motor being operative in response to electronicdrive signals.
 2. The hand-held pipettor of claim 1 further comprisingan encoder assembly associated with said drive motor and operative togenerate feedback signals to said central processing unit indicative ofthe position of the said one stop member.
 3. The hand-held pipettor ofclaim 1 further comprising a sleeve surrounding and axially shiftable onsaid cylinder, said sleeve being urged in one direction into a retractedposition by the pipettor tip removably secured to the said opposite endof said cylinder, and being shiftable in the opposite direction todislodge said pipettor tip from said cylinder.
 4. The hand-held pipettorof claim 3 further comprising spring means for resiliently shifting saidsleeve in the opposite direction.
 5. The hand-held pipettor of claim 4further comprising lock means for accommodating movement of said sleevein the said one direction, and for preventing movement of said sleeve inthe said opposite direction, and manually operable means for releasingsaid lock means to accommodate the resilient shifting of said sleeve inthe said opposite direction.
 6. The hand-held pipettor of claims 4 or 5further comprising pneumatic means for retarding the rate of movement ofsaid sleeve in the opposite direction.
 7. A hand-held pipettorcomprising: a piston received in one end of a cylinder; a pipettor tipremovably secured to an opposite end of said cylinder; manually drivenmeans for reciprocating said piston through a selected stroke toaspirate fluid into and to expel the thus aspirated fluid from saidpipettor tip; mutually spaced members operatively associated with saidmanually driven means for defining a range of said stroke; motor drivenmeans for varying the spacing between said stop members to thereby varythe volume of fluid being aspirated into and expelled from said pipettortip; a sleeve surrounding and axially shiftable on said cylinder, saidsleeve being urged in one direction into a retracted position by thepipettor tip removable secured to the said opposite end of saidcylinder, and being shiftable in the opposite direction to dislodge saidpipettor tip from said cylinder; spring means for resiliently shiftingsaid sleeve in the opposite direction; lock means for accommodatingmovement of said sleeve in the said one direction, and for preventingmovement of said sleeve in the said opposite direction, and manuallyoperable means for releasing said lock means to accommodate theresilient shifting of said sleeve in the said opposite direction; andpneumatic means for retarding the rate of movement of said sleeve in theopposite direction.
 8. The hand-held pipettor of claim 7 wherein saidmotor driven means comprises a drive motor mechanically coupled to oneof said stop members, said drive motor being operative in response toelectronic drive signal.
 9. The hand-held pipettor of claim 7 furthercomprising an encoder assembly associated with said drive motor andoperative to generate feedback signals to said central processing unitindicative of the position of the said one stop member.
 10. A hand-heldpipettor comprising: a piston received in one end of a cylinder; apipettor tip removably secured to an opposite end of said cylinder; amanually driven plunger that is depressible to reciprocate said pistonthrough a selected stroke to thereby aspirate fluid into and to expelthe thus aspirated fluid from said pipettor tip; mutually spaced stopmembers associated with said manually driven plunger to define togetherwith the piston a range of the stroke; a voice recognition andprocessing system that receives verbal commands and provides motorcontrol signals; and a motor that receives the motor control signals andincludes a motor shaft that may be rotated responsive to the motorcontrol signals to vary the range of the stroke defined by the mutuallyspaced stops and the piston to thereby vary the volume of fluid beingaspirated into and expelled from said pipettor tip.
 11. The hand-heldpipettor of claim 10 wherein said motor shaft is mechanically coupled toone of said stop members.